HARMONICS
HARMONICS
(OP)
I have come across an interesting unresloved problem.
A gas cleaner keeps tripping on or around 80% loading. The transformer that feeds this unit is 40kva and the max load kw is around 15kw. The waveform from the unit on the input to the equipment shows chopped waveform on the AC. THere is switching power supply in it I believe. As it attains 80% load, a sudden trip is initiated. I have not done any load study on the transformer yet. Is it possible that some kind of resonance occurs between the caps in the switcher and the inductance created resonance ? I raised the taps on the transformer and the problem goes away. I suspect for some reason the reactive power needs shoot up and this causes the trippings. Any ideas ?
A gas cleaner keeps tripping on or around 80% loading. The transformer that feeds this unit is 40kva and the max load kw is around 15kw. The waveform from the unit on the input to the equipment shows chopped waveform on the AC. THere is switching power supply in it I believe. As it attains 80% load, a sudden trip is initiated. I have not done any load study on the transformer yet. Is it possible that some kind of resonance occurs between the caps in the switcher and the inductance created resonance ? I raised the taps on the transformer and the problem goes away. I suspect for some reason the reactive power needs shoot up and this causes the trippings. Any ideas ?






RE: HARMONICS
respectfully
RE: HARMONICS
If raising tap makes the problem go away, I would think it is because at higher tap, the voltage is high and current goes down. I would suspect the "trip" setting in your "power supply controller" is set at "80%" or it is true RMS sensing and sees higher rms at "80%" you are measuring.
I do not think this is any "problem", but the matter of right settings and voltage.
RE: HARMONICS
RE: HARMONICS
The breaker is not tripping but the power limiter safety device in the tool is tripping. Looking at the power waveform that is drawn into the tool shows power spikes and this happens only during higher power draw close to 14.7kw
When I hooked this device to 45kva transformer it starts tripping at high power levels. When I hook it to larger transformers above 45 kva, there is no trippings. Is it possible that some kind of resonance between the instrument and the transformer is causing sudden power spikes?
The instrument is a plasma generator that takes AC in and converts to DC and then to a DC to DC converter for plasma.
When I increase tap on the 45 kva transformer, there is no tripping.
RE: HARMONICS
RE: HARMONICS
I still think this has to do with voltage and/or the impedance. Does the device draw power in high current pulses? May be at very high current, the tansfromer with lower tap or high impedance can not provide a desired peak voltage, a necessary parameter for proper DC voltage conversion. The unit probably shuts down when it sees lesser peak voltage or chopped voltage. Higher tap or lower impedance source is able to maintain the peak voltage duting a high current draw.
RE: HARMONICS
Of course, we do not know what kind of "gas cleaner" you are talking about. It would help a lot if you describe what you have. And try to forget about resonance for a while. You seem to have fallen in love with that thinking and that makes other thinking difficult for you.
Gunnar Englund
www.gke.org
--------------------------------------
100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...
RE: HARMONICS
Very good point. The setup of the voltage levels can definitely change the efficiency of the motors or other types of machines, which would cause different current outputs.I always go higher settings in order to avoid nuisance trippings. We need to consult with manufactures regarding the machine performances.